Cover Crops in Maize-Second Season Cropping Systems: Cumulative Effects over 19 Years on N¿O and NH¿ Emissions

• Grant number: 25/15871-4
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: December 01, 2025
• End date: November 30, 2026
• Field of knowledge: Agronomical Sciences - Agronomy - Crop Science
• Principal Investigator: Carlos Alexandre Costa Crusciol
• Grantee: Henrique Quintero Piragibe Carneiro
• Host Institution: Faculdade de Ciências Agronômicas (FCA). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil

Abstract

Sustainable intensification of agriculture in the tropics requires practices that combine productivity, soil conservation, and the reduction of environmental impacts. Among these practices, the adoption of cover crops in no-tillage systems has gained prominence, especially in areas with a long-established history of continuous management. This project aims to evaluate the effects of different cover crop strategies intercropped with second-season maize (Zea mays): Urochloa ruziziensis, Crotalaria spectabilis, U. ruziziensis + C. spectabilis, and the absence of a cover crop, on nitrogen dynamics and productive parameters in a soybean-maize rotation system implemented since the 2006/2007 growing season. Ammonia (NH¿) and nitrous oxide (N¿O) emissions will be monitored, along with soil temperature and moisture, dry matter accumulation, straw C/N ratio, and soybean and maize grain yield. Soil nitrogen stock will also be determined down to 1 meter depth, enabling the assessment of nitrogen retention and redistribution in the soil profile after nearly two decades of different management practices. Sampling will be carried out throughout the 2025/2026 crop cycle under real field conditions. It is expected that systems with cover crops, particularly intercropped systems, will present lower nitrogen losses through emissions and improved productive performance. The results of this study may support technical recommendations for more efficient nitrogen management, contributing to the long-term sustainability of tropical agriculture.